Global Comparison of Microwave and Optical Cloud Liquid Water Path Retrievals

In this study, we analyzed one year of spatially and temporally matched microwave and optical cloud liquid water path (CLWP) estimates from the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSRE) and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments. Specifically, microwave CLWPs were produced by the Wentz algorithm, while optical CLWPs were parameterized from MODIS cloud optical thickness and droplet effective radius. We considered both the operational MODIS estimates assuming vertically homogeneous clouds and an adiabatic cloud model, which reduces operational values by approximately 17%. We then systematically investigated differences between AMSR-E and MODIS CLWP retrievals in warm oceanic clouds as a function of a variety of factors such as cloud fraction, geographic location, effective radius profile, cloud temperature, and rain rate.